A Statement by Curtis Larsen, Phd, 13049 Mills Creek Dr

A statement by Curtis Larsen, Phd, 13049 Mills Creek Dr., Lusby, MD 20657 regarding bluff erosion along the Calvert Cliffs:

I received the announcement of the special meeting with Tony O’Donnell on the bluff retreat issues along the Calvert County shoreline while out of the area; therefore, I will be unable to attend the hearings. For some time I have been aware of the precarious and hazardous situation of many homes along the cliffs in the Chesapeake Ranch Estates. I have conducted research on bluff stability and slope evolution along the Calvert Cliffs with the help of my former interns at the U.S. Geological Survey (USGS) prior to my retirement. I should note that I have been retired from the USGS for five years and that I am currently an “emeritus scientist” with the USGS. My comments are my own personal opinions based on my previous research and do not imply any endorsement by the USGS. I wish to direct your attention to a scientific paper published in Shore and Beach magazine by my former interns Inga Clark, Martha Herzog, and me that summarize the results of our work along the cliffs between Flag Harbor and Drum Point. I have attached this paper as a pdf file. A geologic fieldtrip guidebook demonstrating the same study is available online as U.S. Geological Survey Open File Report OFR 03-243*. In simplistic terms, our research found that there are two distinct processes affecting stability of the bluffs along our shores.

The first of these processes is failure of the face of the bluffs as their bases are undercut by ongoing wave action. As this occurs, the faces of the bluffs slough off due to simple gravity. This process results in constant retreat of the bluffs at a rate that has given us a fairly linear shoreline along the cliffs. This process gives rise to our current cliffs that stand at angles of 70 to 80 degrees.

The second process is one of slope retreat. This can be thought of as earth materials slumping or sliding at the tops of steep slopes and retreating to attain a stable angle where earth movements no longer occur. This process is best exhibited in highway construction where road alignments are cut through hills of various earth materials. Highway engineers know that near vertical slopes cannot be maintained without extensive and expensive measures so they design slopes that approximate a near stable angle (depending on the type of earth material). The stable slope angle is often termed the “angle of repose”. This concept has a direct bearing on the problems of our bluff stability. Through our research, we verified that the angle of repose of the materials making up our bluffs is 30 to 35 degrees.

Here is how the two processes relate to our cliffs: Our cliffs stand at 70 to 80 degrees so long as they are allowed to be undercut by wave action and continue to recede at their near constant rate. Were wave action to be eliminated to prevent the bluffs from sloughing and receding, the second process of slope failure would be initiated to cause the bluff tops to retreat until an “angle of repose” is attained. This is a purely natural sequence of events. What was shocking to us when we conducted our studies was that the time required for a near vertical bluff face to fail and retreat to a stable angle of 30 to 35 degrees took place in only 30 years.

This tells us that if we were to try to protect the bases of our bluffs to eliminate wave action and ongoing bluff retreat, it would trigger the second process of slope failure and would result in rapid retreat of the top of the bluff as the slope retreats to try to find a stable angle near 35 degrees. The most common example of how this would occur would be if one was to place rip rap or armor stone along the base of the bluff to protect against wave erosion. The second process would be initiated as a result.

Calvert County planners have attempted to address these processes through zoning requirements for new construction. Calvert County requires setbacks of one and one half times the height of the bluff plus an additional 20 feet for new building. For a 100 foot bluff, a setback of 170 feet from the active edge of the bluff would be required. Unfortunately, our communities of Scientist Cliffs, Chesapeake Ranch Estates, and Drum Point were platted before there was recognition of these bluff processes. As a result, houses were allowed to be built near the edge of the bluffs. Perhaps more significantly, homes that were built 20 to 30 years ago at safer distances from the bluff edge faced constant bluff retreat that moved the bluff edge to the house location.

Frankly, I am concerned each time we sail past the cliffs and see armor stone placed on beaches at the base of the cliffs. The processes I mentioned above are purely natural and are pretty hard to sidestep. Engineering approaches to stabilize slopes like these are possible but are extremely expensive. One approach has been used by a property owner immediately south of Cove Point. This system used an offshore breakwater to act as the toe to an artificial slope that was later placed as a buttress against the failing bluff to form the proper stable slope angle. This type of engineering remedy required placement of large amounts of fill. The property is apparently bounded by ravines on either side so that the artificial obstruction of long shore transport of sediment did not seem evident.

Another type of engineering approach that might be tried would be to “pin” the near vertical slope with vertical pilings driven behind the face of the slope to keep the top of the bluff from failing. This would be accompanied with horizontal anchors to help retain the top of the slope as well as horizontal drains to dewater the sediments. I think the standard approach would be to cover the exposed face of the bluff with mesh and then coat it with a concrete type of mixture to cover the exposed soils from weathering. This technique or similar ones would also be quite expensive. The major problem with this approach is that the bluffs extend continuously both north and south of the existing houses. Any attempt to fix the face of the bluff to protect an individual property would not protect the neighboring land. The adjacent bluffs would continue to recede at the current rate of retreat and tend to outflank the individual’s “protected” property. Over time this would leave the individual property as a small peninsula unprotected on either side with possibly more rapid bluff erosion to the south.

Geologists are often seen as negative people who identify but offer no solutions to natural earth hazards. On the other hand those who offer immediate and seemingly constructive solutions are often seen in a more positive light. In spite of this I cannot help but voice my concerns.

I can offer no immediate solutions to individual property owners’ problems. There are clearly engineering approaches that may seem more immediate and positive. I know that property owners are frantic about losing home and investment. What I also know is that this problem is larger than individual property owners along the shoreline at Chesapeake Ranch Estates. On the one hand we have to face the fact that the slopes that form the Calvert Cliffs have been steadily receding for at least 4,000 years. On the other, we have to confront the social issues that have left property owners along the cliffs in such a precarious position.

I hope that the various meetings set up with Delegate O’Donnel l will consider more than protection of individual residences. In an ideal world my hope would be that the State of Maryland could and would purchase the lands comprising all the Calvert Cliffs and help remove property owners from the problem of bluff failure. Clearly this is not a practical solution. However, my sense is that County, State, and private groups could help by combining efforts to both protect properties and protect future property owners from these experiences. As mentioned above, Calvert County has already developed zoning restrictions for construction near the edge of the bluffs. It would appear in some cases those homeowners’ attempts to move their homes away from the edge of the bluffs have been met by contradictory County codes that restrict placement of homes on existing sites. In other cases it would seem that County setback codes are not rigidly enforced. At the same time, State, County, and community seem reticent to find ways to remove the lands bordering the cliffs from individual tax bases. On the one hand, any attempt by the State or County to acquire these hazardous lands to protect future property owners can be seen as a “taking” of private lands. On another hand, private (currently called “commonly owned infrastructure) communities tend to see these lands bordering the cliffs in terms of their property value as well, but in addition do not want to sacrifice community road fees or STD (special tax district) income. Public funds cannot be used to solely protect private or individual properties especially in the eyes of taxpayers living away from the shoreline. On the “private” side of the issue current property owners along the failing bluffs do not want lose what they see as high value property with spectacular views of Chesapeake Bay.

The leading question is “what can be done?”

I would suggest that the first step is for communities like the Chesapeake Ranch Estates to adopt a strategy that recognizes the edges of the bluffs as natural geologic hazards rather than income. In addition, it is important to recognize that the problem of bluff failure is beyond the scope of expensive engineering techniques. Such approaches would seem to be beyond the STD limits property owners would be willing to pay—especially those living away from the shoreline or the non-resident property owners. In short, I do not think that a private community could afford to either engineer the bluffs or purchase the lands to form a protective buffer zone along the bluff edge.

My hope is that the disparate parties concerned with bluff failure and personal safety can see that bluff retreat is a constant process that cannot be dealt with as a simple engineered solution. In my opinion it would further the “common good” to:

1. Set aside a “protective buffer zone” along the edges of the retreating bluff edges that conform to or approximate the current County zoning setbacks. This could be accomplished in combination with the Federal, State, County, and “private” community concerned through tax relief and/or buyouts to property owners. One way to attain this might be through conversion of “commonly-owned” community property along the bluff edge to non-buildable “green space.” Another avenue open to property owners might be through granting an environmental easement to land bordering the bluff to an existing land trust in the County or by outright donation to a 501 (c)3 organization for a deduction of property value from Federal and State taxes. The key to any such approach would be tax relief and this responsibility would fall squarely on the shoulders of the stated governing bodies.

2. Ensure that lands are set aside for the “common good” as a protective buffer from erosion and bluff failure and have perpetual protection from future development. Further, provisions need be made for subsequent addition to such a buffer as the bluffs continue to retreat.

3. Recognize that the solution to this natural hazard is a social concern and requires a social answer beyond the very real concerns of individual homeowners and that the most effective approach is to remove people from the problem through protective land use.

To summarize, research carried out on the stability of the Calvert Cliffs points out their continued retreat over the past 4,000 years. The bluffs are affected by two distinct mass wasting processes. The first, “bluff retreat” is a constant sloughing off of the bluff face as the toe of the bluff is undercut by wave erosion. This is the process most prevalent at present and results in bluff retreat at a rate that tends to maintain a linear shoreline with a slope angle of 70 to 80 degrees. The second process is “slope retreat” that occurs if and when wave erosion at the base of the bluff ends by either natural or man induced changes. This results in relatively rapid failure of the top of the bluffs and continues until the bluff evolves into a stable slope of 30 to 35 degrees. Our research shows that this change south of Flag Harbor takes place over 30 years—the length of a mortgage. We concluded that simple engineering methods to protect against wave erosion at the base of the bluff would tend to trigger the second process of slope retreat. While more complicated and costly engineering approaches might be effective in maintaining the near vertical bluff face and protect an existing property initially, adjacent bluff retreat would tend to outflank the “protected” property as the bluffs continue to recede on either side.

It is my personal view that the best long term approach to the protection of both people and property along the Calvert Cliffs is the establishment of protective buffers along the retreating bluff edges that adhere to or approximate the setbacks established by the County’s Department of Planning and Zoning. I recommend a combined effort by Federal, State, County, Community, and private groups (such as land trusts) to work with property owners to create such a buffer. This could only be achieved through significant tax relief as incentive to owners of threatened properties.

*Various of my publications on Chesapeake Bay and sea level can be viewed online with key word searches for my name: Curt or Curtis Larsen and Chesapeake Bay.